In a battlefield scenario, the lethality and survivability of an aircraft or ground vehicle often critically depends on the effectiveness of the target acquisition and fire control technology that the vehicle employs. An important aspect of any target acquisition and fire control system is the ability see or image a target. In target acquisition and fire control technology, four stages of target imaging quality are important: (1) detection, (2) classification, (3) recognition, and (4) identification. Detection is defined as the ability to discern a signal that may be a target. Classification is defined as the ability to discern that the target is, for example, a tracked or a wheeled vehicle. Recognition is defined as the ability to determine the type of vehicle, such as a tank or an armored personnel carrier. Identification is defined as the ability to determine the type of tank, e.g., a Soviet T-72 tank versus a U.S. M-1 tank.
In a typical imaging sensor system, target classification requires about three times as many lines across the target as is required for detection. Recognition generally requires four times as many lines across the target, and identification requires eight times as many lines as is required for detection. Tactical targets emit infrared radiation that a thermal imaging sensor (TIS) receives to detect the target. Generally, a TIS can detect a target with two or fewer lines across the target. This means that, under "normal" conditions (i.e., mid-latitude summer day with 5-kilometer visibility), detection by a TIS will occur at 8 kilometers, whereas recognition ranges are significantly less (i.e., approximately 3.8 kilometers). An aircraft or tank commander cannot release a weapon until he recognizes the target. Once a pilot has recognized a target, a finite amount of time is required to actually release a weapon. Therefore, weapon release usually will be at ranges less than 3.8 kilometers. Hence, the farther away an aircraft pilot or tank commander, for example, can recognize a target, the greater will be the aircraft's or tank's success in attacking and surviving an attack from an enemy vehicle having equally effective weapons.
In an air-to-ground combat scenario, the large difference in detection and recognition ranges that conventional target recognition systems demand requires a pilot to maintain line-of-sight contact with the target while his aircraft moves into closer range. This causes the aircraft to enter a more dangerous zone and to remain exposed for a longer time period. This reduces the probability that the aircraft can survive the attack. Also, a reduced recognition range lowers the weapon release range and, thereby, restricts the number of weapons that a pilot can release to different targets on the same pass.
Techniques heretofore known to increase TIS recognition ranges supply additional magnification. These systems, however, are too heavy and expensive to be practical for tactical aircraft. A second approach to target detection and recognition has been the use of television systems. Because television systems require illumination for adequate imaging, however, they have substantial operational limitations. Conventional television systems use lasers as the illuminating source for imaging. When a television-laser system is used in a search and detect mode, obtaining a reasonable probability of finding a target requires a fairly wide field-of-view. Illuminating the necessary field-of-view for such applications (typically 4 to 30 degrees), however, requires extremely high power laser sources. These laser sources are so large that they, also, are impractical for use on tactical aircraft.
Therefore, a need has arisen for a system that is compatible with tactical aircraft that increases a target's recognition range to near or equal the target detection range.
There is a need for a method and system that provides longer range target recognition, and that clearly avoids the weight, expense, size, and large illumination field-of-view problems of known systems that seek to increase target recognition ranges.